APPARATUS AND METHOD FOR DISPENSING SMALL QUANTITIES OF PARTICLES

摘要

There is disclosed an apparatus and method which is capable of dispensing ve ry small (typically less than 5 mg) quantities of particles to a high accuracy in a repeatable way and without undue wastage. Also, the need for advanced particle formulation is reduced. The apparatus comprises a closed loop contr ol system which uses an electro-mechanical actuator to deliver impact energy to a supply of particles initially held on a sieve in a hopper. The impact energy causes a small number of particles to fall through the sieve and onto a weig ht measuring balance. The weight obtained is scrutinised by a processor to see if further actuations are required. In preferred embodiments, the energy of actuation is varied in accordance with the rate of dispensation calculated b y the processor. Also, a correction amount can be obtained to take account of the fact that the balance can take a considerable amount of time to settle t o its final value.